The present invention relates to a support assembly, and in particular to a support assembly for incorporation into a seat frame in order to provide a seat structure with an adjustable degree of support in two different regions, e.g. a lumbar region and a pelvis region. More specifically, the present invention relates to a support assembly comprising a support member for providing load bearing support for upholstery of a seat.
Support assemblies of the aforementioned kind are very well known and may have various configurations determined by the design of a seat in which the support assembly is to be mounted (see, e.g., WO 95/00039 A).
EP 0 874 575 B1 proposes a support assembly for incorporation into a seat frame, the support assembly comprises a wire framework having two lateral side wires suspendable in the seat frame and a plurality of transverse wires providing load bearing support for upholstery of the respective seat and extending between the lateral side wires.
Support assemblies of the aforementioned kind are incorporated in a seat frame of a back rest in order to support the lumbar region of a person sitting on the respective seat. When using a support assembly having a wire framework of the kind described above, this can be accomplished by pulling the two lateral side wires of the wire framework towards the front of the back rest of the seat. For example, EP 0 552 904 A1 discloses such a lumbar support assembly comprising a support member in the form of a platform element, which is suspended by tension springs in a seat frame to support the cushioning of a back rest. The support member has two lateral side wires and a plurality of transverse wires, and two adjustment arrangements comprising Bowden cables are linked between respective portions of the lateral side wires to apply a force of longitudinal compression, whereby the side wires are caused to be hinged outwardly at an articulation point to vary the degree of lumbar support provided by the transverse wires.
Since the two sides of the support member of the support assembly should be displaced by the same amount at the same time for achieving a symmetric support feeling, it is necessary to shorten the extension of both Bowden cables by a respective actuator mechanism simultaneously, which however is difficult to achieve and requires two separate Bowden cables.
Further, it is known to provide lumbar support assemblies not only with an adjustable degree of support, but also with an adjustable height, which means that a vertical position of the region in which the support is provided can be adjusted. For this purpose, it is typically required to have one mechanism for adjusting the degree of support and a further mechanism for adjusting the height. Moreover, it is necessary to have two separate actuators for independently adjusting the height and the degree of support.
From GB 2 342 286 A, a support assembly is known which comprises a support member to be suspended in a seat frame and adjustable link means for varying the effective profile of the support. In particular, a plurality of the adjustable link means is provided which are spaced apart in a vertical direction of the seat frame, which allows for adjusting the degree of support in vertically different regions of the support member. Also in this case, two separate adjustment arrangements or adjustment mechanisms comprising Bowden cables and an actuator are required for each of the different support regions.
In the above-known support assemblies, there exists therefore a problem as to a large number of components which have to be used for achieving a symmetric adjustable support in different regions. This increases costs of the seat, and may also result in problems as to accommodating the various components within the seat structure.
In this respect, EP 05 019 763 proposes a support assembly in which a first Bowden cable arrangement for adjusting the degree of support in a first support region and a second Bowden cable arrangement for adjusting the degree of support in a second support region are actuated by a single actuator configured to simultaneously act, in opposite directions, on the first Bowden cable arrangement and on the second Bowden cable arrangement.